feat(frontend): add API client, layout, and routing

- Create Axios-based API client with sources, jobs, and dashboard endpoints
- Add responsive Layout component with navigation sidebar
- Set up React Router with Dashboard, Backups, and Settings routes
- Configure TanStack Query provider with default options
- Use lucide-react for navigation icons

frontend/node_modules/@vitest/expect/README.md

@@ -0,0 +1,17 @@
+# @vitest/expect
+
+Jest's expect matchers as a Chai plugin.
+
+## Usage
+
+```js
+import * as chai from 'chai'
+import { JestAsymmetricMatchers, JestChaiExpect, JestExtend } from '@vitest/expect'
+
+// allows using expect.extend instead of chai.use to extend plugins
+chai.use(JestExtend)
+// adds all jest matchers to expect
+chai.use(JestChaiExpect)
+// adds asymmetric matchers like stringContaining, objectContaining
+chai.use(JestAsymmetricMatchers)
+```